Until recently, most wireless communications sites included radio systems that were located on the ground level in a building, cabinet or other shelter. The DC power supply, baseband controller, amplifiers and radios were historically located in one location within the shelter. From this location, coaxial cable was run from the radios to antennas that were supported on a tower outside the building. Equipment installed in this manner is susceptible to lightning strike damage either due to lightning strikes directly hitting the antennas or from induced energy from the tower structure. Coaxial lightning protectors are commonly used to protect the antennas on the tower and radios on the ground. The DC power plant is somewhat isolated from direct lightning events, due to the radios, other dc-powered equipment and grounding obstructing the path of the lightning strike to earth.
Latest generation wireless communications systems, referred to as distributed antenna systems (DAS), distributed DC radio systems, remote radio heads (RRH), 4G and long term evolution (LTE) cellular communication systems, now commonly locate the radios next to the antennas on the tower outside of the communications shelter. In these next-generation facilities, the baseband system module that controls the radio traffic is still located at the ground level shelter, but the actual radios are separated from the controllers up to several hundred feet and controlled by fiber optic links. The radios are powered directly by DC feeds from the DC power plant that extend up the tower and to the radios. In some cases, the DC cables and fiber optic cables are run separately up the tower and in other cases they are all bundled together in one large hybrid cable.
The radios located outside of the communications shelter on top of the tower are much more susceptible to damage from lighting strikes and other electrical power surge events. Individual power lines are run to each individual radio also increasing the amount of power cabling exposed to power surge events. Thus, the DC power plant and telecommunication equipment at communication stations with distributed power have more risk of being damaged due to direct lighting strikes and power surges.